Ropes, cables and other such lines are often employed to stabilize and erect various objects. Typical of such uses for these lines is the erection of tents, clotheslines and the like and the stabilization of poles, antennas and the like. In order that the elements being retained in place by the lines employed are securely retained, it is important to tension the lines as taut as possible. In the past, either turnbuckles or various knots have been employed to maintain tension in the lines. Knots can only be as tight as origionally tensioned. Further, knots tend to loosen over time, thus the tension does not remain at the origional level. Turnbuckles do maintain even tensions, however, they often are difficult to erect. It is desirable, therefore, to provide a tensioning device for various types of lines which is simple for a single operator to use and which maintains a constant tension on the lines without slippage.